This adds a simple module for testing the kernel's printffacilities. Previously, some %p extensions have caused a wrong returnvalue in case the entire output didn't fit and/or been unusable inkasprintf(). This should help catch such issues. Also, it should helpensure that changes to the formatting algorithms don't break anything.

I'm not sure if we have a struct dentry or struct file lying around atboot time or if we can fake one, but most %p extensions should betestable, as should the ordinary number and string formatting.

The nature of vararg functions means we can't use a more conventionaltable-driven approach.

For now, this is mostly a skeleton; contributions are verywelcome. Some tests are/will be slightly annoying to write, since theexpected output depends on stuff like CONFIG_*, sizeof(long), runtimevalues etc.